Toothbrush



Oct. si, 1933. AKIZAWA 1,932,878

TOOTHBRUSH Filed Aug. 27, 1952 I'nre 77 fan- Patented Oct. 31, 1933UNITED STATES PATENT OFFICE Application August 27, 1932, Serial No.630,734, and in Japan September 5, 1931 1 Claim.

This invention relates to improvements in a tooth brush which comprisesa shank and a detachable bristle back member. It has for its object toprovide a rigid and reliable holding means for the bristle back member,which is rotatably held on a knob on the shank so that it rotates whileit is in use, and the bristles are evenly wom all over the surtace.

Fig. 1 is a side elevation of the brush accordr ing to this invention,and

thereof.

Fig. 3 is a part sectional elevation of the shank. Fig. 4 is a sectionalelevation of the bristle back member, and Fig. 5 is a plan view thereof.

The tooth brush of this invention consists of a shank and a bristle backmember which is detachably held by the shank, the holding means beingthe characteristic feature of this invention.

Rererring to the drawing, an end of the shank 1 is somewhat flattenedand widened so as to make a spoon-like shape. At the centre of theflattened end is fixed a knob 2 which may be made integral with theshank, or separately therei'rom and flrmly fixed thereto with a ce- 5menting material. According to the example shown in Fig. 3, the knob 2is made of a metal having a grooved flange za, the latter part beingmoulded in the body of the shank.

The bristle baekmember has a base plate 3 with bristle 4 set therein. Onthe back side of the plate is moulded therein in a spring member, whichcomprises a spring 5 and a case 6 therefor. The case has a centralprojection sa, and each end of the spring 5 fits into the slits 6b 5 onthe opposite side of the central projection. The size of the centralprojection is such that the knob of the bristle back member can beloosely inscrted into the cavity of the projection.

Fig. 2 is a plan view When the knob fits into the cavity, the spring'sends flrmly hold the neck of the knob so that the bristle back member isconnected to the shank although the former can freely rotate on thelatter.

The shank and the base plate of the bristle back member can be made ofany convenient material, but a plastic material such as celluloid andresinous compounds is preferable, because the knob and the spring membercan be moulded in the bodies of the shank and the base plate withoutrequiring any cementing material.

The tips of the bristles are cut so as to make a concentric wave form asshown in Fig. 2, thereiore the sectinal view of the bristle on anyradial plane is the same as shown in Fig. 4.

When this tooth brush is in use, the bristle member rotates on the knob2 by the triction on the teeth, so that each part of the bristle wearsin the same manner and at the same speed, therefore a bristle memberlasts longer. In case the bristle is wo-n off, it may be replaced by anew one, and the shank can be used for a long time.

What I claim is:-

A tooth brush which comprises a shank and a bristle back memberdetachably held by the former, the holding means consisting of a knobprovided at an end of the shank and a spring member provided at thecentre of the base plate of the bristle back member which base plate ismade in a circular disc form. the knob being rotatably held by thespring member. and the tips of the bristles of the bristle back memberbeing cut in concentric wave form.

KUNIYOBHI AKIZAWA.

